Looking different improves 'survival' among animals of same species

Washington, July 24 (ANI): If you are confused as to why animals of the same species sometimes look very different from each other, biologists in England have an answer.

Writing in the latest issue of Evolution, University of York experts have used the term 'exuberant polymorphisms' for this natural phenomenon.

They also say that they have developed computer models that may help explain how this level of variation arises and persists.

Dr. Geoff Oxford, in the University's Department of Biology, studied the Hawaiian Happy-face Spider, which the researcher says is a prime example of an exuberant polymorphism.

The biologist points out that the variations range from a common plain yellow form to rare types sporting red, black or white marks, all of which are inherited.

Dr. Oxford said: "It has always been a real mystery why every population of this spider across different Hawaiian islands contains such high levels of variation. This was the starting point for our models."

The York study suggests that 'dietary wariness'-a hesitancy of predators to consume a novel food item and a consequent reluctance to incorporate it into their regular diet-may explain the sheer number of distinct forms involved in the exuberant polymorphisms of some species.

According to the study, a modest level of predator dietary wariness can lead to the maintenance of large numbers distinct prey forms within a single species.

Dr Daniel Franks, of the University's York Centre for Complex Systems Analysis, said: "A mutant prey individual that looks different from its fellows has a survival advantage because it will be unfamiliar to predators that will be reluctant to change their diet to accommodate it. Some prey species have evolved polymorphisms to deter predators by presenting them with a large number of visually novel foods." (ANI)